Some fuels burned by oil lamps produce relatively large amounts of smoke, but are still in use because they have other beneficial properties. For example, citronella oil produces smoke but is useful for repelling insects, such as mosquitoes. Although a citronella lamp user can avoid the buildup of smoke by extinguishing the lamp and relighting it later, this is undesirable because it extinguishes the light source. Although the amount of light produced by citronella oil is less than other types of liquid fuels, it is nonetheless convenient to have this light source and many users find the pink colored flame to be attractive.
Air drafts around the flame tend to increase the amount of smoke produced, so some existing lamps provide a shield around the flame to protect from drafts. However, shielding the flame from drafts can result in an inadequate air supply to the flame. This inadequate air supply results in incomplete combustion, which also tends to increase the amount of smoke produced.